Acceptability limits based on biology goals in haematology EQAS

The current situation in defining and setting criteria used to determine acceptability limits in haematology external quality assessment schemes (EQAS) is discussed. This report also addresses the control materials and experiences used when determining the suitability of home-made material for complete blood count (CBC), which involves testing a small scheme of about 100 participants with different analytical systems based on a single principle for the attainment of quality specifications. By studying the biological variation in haemocytometry using home-made EQA control blood in a controlled study that employed only haematological analysers based on the electrical impedance (Coulter) principle, we have assessed whether total error goals are achieved for the following parameters: white blood cell (WBC), red blood cell (RBC), and platelet (Plt) counts, concentration of haemoglobin (Hb), and mean cell volume (MCV) in a simple single challenge external quality assessment scheme. We found that we could not attain the biological goals for MCV, RBC and Plt in a haematology EQAS that uses the single analytical principle; even minimum performance based upon the calculation of 1.65[0.75CV_I] + 0.375[CV_I² + CV_G²]^1/2 (p<0.05) is not achievable. For the other two parameters, the minimum (Hb) required for desirable performance (Lkci), given by 1.65[0.50CV_I] + 0.25[CV_I² + CV_G²]^1/2 (p<0.05), is achievable, but the optimum performance of 1.65[0.25CV_I] + 0.125[CV_I² + CV_G²]^1/2 (p<0.05) is not attainable for all five basic haemocitometry parameters. Besides acceptability limits, the control materials used for CBC and the target values used in haematology EQAS are discussed from a practical point of view in order to improve quality.     

Estimation of the biological variation of glucose-6-phosphate dehydrogenase in dried blood spots

Models based on biological variation provide a well-accepted database with reliable information for clinical laboratories for all purposes including screening, diagnosis and follow-up. Newborn screening laboratories use a blood spotted paper matrix to measure the analytes. This matrix medium is certainly different than body fluid matrix medium. After long-term monitoring of the performance of the Glucose-6-Phosphate Dehydrogenase Kit (R&D Diagnostics OSMMR 2000-D G6PD), the results obtained from the variation analysis were statistically evaluated. Analytical coefficient of variation, CV _A, was found to be 5.41%. The CV _A derived from between run assays was 5.32%, while within-subject biological coefficient of variation, CV _I, was 7.26%. Since minimum performance is defined as CV _A< 0.750 CV _I , CV _A should be lower than 5.44%. The analytical bias in calculation of total error was chosen to evaluate the performance of this assay. In this aspect, CV _G, between-subject biological coefficient of variation, was found to be equal to 10.35%. B _A was found to be 4.12%, which is lower than 4.74%, which means that it is acceptable. Therefore, the minimum quality specification for total error allowable is . When the relevant results obtained in this study were substituted in this formula, TE _a was found to be 13.7% for G6PD measurement in dried blood spots on paper filter matrix. It is expected that this figure will be helpful for the performance evaluation of newborn screening laboratories performing G6PD screening. We have been using error grid graphs for the evaluation of our external quality assurance survey results for the last two years, only because there was no data for assays employing filter matrix. Even the TE _a already reported for EDTA whole blood samples used in G6PD assays has been remarkably high, which can easily create the wrong impression that G6PD is not a reliable test to perform from blood spot cards. The present study shows that this assay is adequately reliable even when performed from dried blood spot matrix. However, we believe that the combination of total allowable error, error grid graphs with a well-defined cut off is the best approach to obtain an accurate performance evaluation for this test.Presented at the 10th Conference Quality in the Spotlight, March 2005, Antwerp, Belgium.     

Thermal decomposition kinetics of bis(pyridine)manganese(II) chloride

The thermal stability and the decomposition steps of bis(pyridine)manganese(II) chloride (Mn(py)₂Cl₂) were determined by thermogravimetry and derivative thermogravimetry. The initial compound and the solid compounds resulted from each step of decomposition were characterized by FT-IR spectroscopy and RX diffraction. It was pointed out that at the progressive heating of Mn(py)₂Cl₂, the following decomposition reactions occur: I $$ {\text{Mn}}\left( {\text{py}} \right)_{ 2} {\text{Cl}}_{ 2} \left( {\text{s}} \right) \, \to {\text{ Mn}}\left( {\text{py}} \right){\text{Cl}}_{ 2} \;\left( {\text{s}} \right) \, + {\text{ Py }}\left( {\text{g}} \right) $$ II $$ {\text{Mn}}\left( {\text{py}} \right){\text{Cl}}_{ 2} \left( {\text{s}} \right) \, \to {\text{ Mn}}\left( {\text{py}} \right)_{ 2/ 3} {\text{Cl}}_{ 2} \;\left( {\text{s}} \right) \, + { 1}/ 3 {\text{ Py }}\left( {\text{g}} \right) $$ III $$ {\text{Mn}}\left( {\text{py}} \right)_{ 2/ 3} {\text{Cl}}_{ 2} \left( {\text{s}} \right) \, \to {\text{ MnCl}}_{ 2} \left( {\text{s}} \right) \, + { 2}/ 3 {\text{ Py }}\left( {\text{g}} \right) $$ The dependence of the activation energy of these decompositions steps on the conversion degree, evaluated by isoconversional methods, shows that all decomposition reactions are complex. The mechanism and the corresponding kinetic parameters of reaction (I) were determined by multivariate non-linear regression program and checked for quasi-isothermal data. It was pointed out that the reaction (I) consists of three elementary steps, each step having a specific kinetic triplet.     

Iodine Hydrolysis Equilibrium

The equilibrium constant for the hydrolytic disproportionation of I₂

Electrochemical Studies on <Emphasis Type="Italic">cis</Emphasis>-[Cr<Superscript>III</Superscript>(bipy)<Subscript>2</Subscript>(SCN)<Subscript>2</Subscript>]I<Subscript>3</Subscript> (Where bipy Denotes 2,2′-Bipyridine) in Acetonitrile

The molar conductivities (Λ) of solutions of bis(2,2′-bipyridine)bis(thiocyanate)chromium(III) triiodide [Cr^III(bipy)₂(SCN)₂]I₃ (where bipy denotes 2,2′-bipyridine, C₁₀H₈N₂), [ _3^-\mathrm{A}^{+}\mathrm{I}_{3}^{-} ], were measured in acetonitrile (ACN) at the temperatures 294.15, 299.15, and 305.15 K. In addition, cyclic voltammograms (CVs) of [ A⁺I₃^-\mathrm{A}^{+}\mathrm{I}_{3}^{-} ] were recorded on platinum, gold, and glassy carbon working electrodes in ACN, using n-tetrabutylammonium hexafluorophosphate (NBu₄PF₆) as the supporting electrolyte, at scan rates (v) ranging from 0.05 to 0.12 V⋅s⁻¹. Furthermore, electrochemical impedance spectroscopic (EIS) measurements were carried out in the frequency range 50 Hz<f<50 kHz using these three working electrodes. The measured molar conductivities (Λ) demonstrate that [ A⁺I₃^-\mathrm{A}^{+}\mathrm{I}_{3}^{-} ] behaves as uni-univalent electrolyte in ACN over the investigated temperature range. The Λ values were analyzed by means of the Lee-Wheaton conductivity equation in order to estimate the limiting molar conductivities (Λ _o), as well as the thermodynamic association constants (K _A), at each experimental temperature for formation of [A⁺ I₃^-\mathrm{I}_{3}^{-} ] ion-pairs. The limiting ionic conductivities ( l_±^o\lambda_{\pm}^{\mathrm{o}} ), the diffusion coefficients at infinite dilution (D _±), as well as the Stokes’ radii (r _St) were determined for both A⁺ and I₃^-\mathrm{I}_{3}^{-} ions. The thermodynamic parameters for the ionic association process, i.e. the Gibbs energy ( DG_A^o\Delta G_{\mathrm{A}}^{\mathrm{o}} ), enthalpy ( DH_A^o\Delta H_{\mathrm{A}}^{\mathrm{o}} ), and entropy ( DS_A^o\Delta S_{\mathrm{A}}^{\mathrm{o}} ), were also determined. The mobility and diffusivity of the A⁺ ion increase linearly with increasing temperature because the solvent medium becomes less viscous as the temperature increases. The K _A values indicate that significant ion association occurs that is not influenced by temperature changes. The ion-pair formation process is exothermic ( DH_A^o < 0\Delta H_{\mathrm{A}}^{\mathrm{o}}<0 ), leading to the generation of additional entropy ( $\Delta S_{\mathrm{A}}^{\mathrm{o}}>0$\Delta S_{\mathrm{A}}^{\mathrm{o}}>0 ). As a result, the Gibbs energy DG_A^o\Delta G_{\mathrm{A}}^{\mathrm{o}} is negative ( DG_A^o < 0\Delta G_{\mathrm{A}}^{\mathrm{o}}<0 ) and the formation of [A⁺I₃^-][\mathrm{A}^{+}\mathrm{I}_{3}^{-}] becomes favorable. CV studies on [A⁺I₃^-][\mathrm{A}^{+}\mathrm{I}_{3}^{-}] solutions indicated that the redox pair Cr^3+/2+ appears to be quasi-reversible on a glassy carbon electrode but is completely irreversible on platinum and gold electrodes. EIS experiments confirm that, among these three electrodes, the glassy carbon working electrode has the smallest resistance to electron transfer.     

Thermochemistry of paracetamol

Combustion calorimetry, Calvet-drop sublimation calorimetry, and the Knudsen effusion method were used to determine the standard (p ^o = 0.1 MPa) molar enthalpies of formation of monoclinic (form I) and gaseous paracetamol, at T = 298.15 K: \Updelta_\textf H_\textm^\texto ( \textC ₈ \textH ₉ \textO ₂ \textN,\text cr I ) = - ( 4 10.4 ±1. 3)\text kJ  \textmol ^{- 1} \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} \left( {{\text{C}}_{ 8} {\text{H}}_{ 9} {\text{O}}_{ 2} {\text{N}},{\text{ cr I}}} \right) = - ( 4 10.4 \pm 1. 3){\text{ kJ}}\;{\text{mol}}^{ - 1} and \Updelta_\textf H_\textm^\texto ( \textC ₈ \textH ₉ \textO ₂ \textN,\text g ) = - ( 2 80.5 ±1. 9)\text kJ  \textmol ^{- 1} . \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} \left( {{\text{C}}_{ 8} {\text{H}}_{ 9} {\text{O}}_{ 2} {\text{N}},{\text{ g}}} \right) = - ( 2 80.5 \pm 1. 9){\text{ kJ}}\;{\text{mol}}^{ - 1} . From the obtained \Updelta_\textf H_\textm^\texto ( \textC ₈ \textH ₉ \textO ₂ \textN,\text cr I ) \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} \left( {{\text{C}}_{ 8} {\text{H}}_{ 9} {\text{O}}_{ 2} {\text{N}},{\text{ cr I}}} \right) value and published data, it was also possible to derive the standard molar enthalpies of formation of the two other known polymorphs of paracetamol (forms II and III), at 298.15 K: \Updelta_\textf H_\textm^\texto ( \textC ₈ \textH ₉ \textO ₂ \textN,\text crII ) = - ( 40 8.4 ±1. 3)\text kJ  \textmol ^{- 1} \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} \left( {{\text{C}}_{ 8} {\text{H}}_{ 9} {\text{O}}_{ 2} {\text{N}},{\text{ crII}}} \right) = - ( 40 8.4 \pm 1. 3){\text{ kJ}}\;{\text{mol}}^{ - 1} and \Updelta_\textf H_\textm^\texto ( \textC ₈ \textH ₉ \textO ₂ \textN,\text crIII ) = - ( 40 7.4 ±1. 3)\text kJ  \textmol ^{- 1} . \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} \left( {{\text{C}}_{ 8} {\text{H}}_{ 9} {\text{O}}_{ 2} {\text{N}},{\text{ crIII}}} \right) = - ( 40 7.4 \pm 1. 3){\text{ kJ}}\;{\text{mol}}^{ - 1} . The proposed \Updelta_\textf H_\textm^\texto ( \textC ₈ \textH ₉ \textO ₂ \textN,\text g ) \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} \left( {{\text{C}}_{ 8} {\text{H}}_{ 9} {\text{O}}_{ 2} {\text{N}},{\text{ g}}} \right) value, together with the experimental enthalpies of formation of acetophenone and 4′-hydroxyacetophenone, taken from the literature, and a re-evaluated enthalpy of formation of acetanilide, \Updelta_\textf H_\textm^\texto ( \textC ₈ \textH ₉ \textON,\text g ) = - ( 10 9. 2 ± 2. 2)\text kJ  \textmol ^{- 1} , \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} \left( {{\text{C}}_{ 8} {\text{H}}_{ 9} {\text{ON}},{\text{ g}}} \right) = - ( 10 9. 2\,\pm\,2. 2){\text{ kJ}}\;{\text{mol}}^{ - 1} , were used to assess the predictions of the B3LYP/cc-pVTZ and CBS-QB3 methods for the enthalpy of a isodesmic and isogyric reaction involving those species. This test supported the reliability of the theoretical methods, and indicated a good thermodynamic consistency between the \Updelta_\textf H_\textm^\texto \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} (C₈H₉O₂N, g) value obtained in this study and the remaining experimental data used in the \Updelta_\textr H_\textm^\texto \Updelta_{\text{r}} H_{\text{m}}^{\text{o}} calculation. It also led to the conclusion that the presently recommended enthalpy of formation of gaseous acetanilide in Cox and Pilcher and Pedley’s compilations should be corrected by ~20 kJ mol⁻¹.     

Inner-sphere oxidation of a ternary dipicolinatochromium(III) complex involving a malonic acid co-ligand

The oxidation of a ternary complex of chromium(III), [Cr^III(DPA)(Mal)(H₂O)₂]^?, involving dipicolinic acid (DPA) as primary ligand and malonic acid (Mal) as co-ligand, was investigated in aqueous acidic medium. The periodate oxidation kinetics of [Cr^III(DPA)(Mal)(H₂O)₂]^? to give Cr(VI) under pseudo-first-order conditions were studied at various pH, ionic strength and temperature values. The kinetic equation was found to be as follows: \( {\text{Rate}} = {{\left[ {{\text{IO}}_{4}^{ - } } \right]\left[ {{\text{Cr}}^{\text{III}} } \right]_{\text{T}} \left( {{{k_{5} K_{5} + k_{6} K_{4} K_{6} } \mathord{\left/ {\vphantom {{k_{5} K_{5} + k_{6} K_{4} K_{6} } {\left[ {{\text{H}}^{ + } } \right]}}} \right. \kern-0pt} {\left[ {{\text{H}}^{ + } } \right]}}} \right)} \mathord{\left/ {\vphantom {{\left[ {{\text{IO}}_{4}^{ - } } \right]\left[ {{\text{Cr}}^{\text{III}} } \right]_{\text{T}} \left( {{{k_{5} K_{5} + k_{6} K_{4} K_{6} } \mathord{\left/ {\vphantom {{k_{5} K_{5} + k_{6} K_{4} K_{6} } {\left[ {{\text{H}}^{ + } } \right]}}} \right. \kern-0pt} {\left[ {{\text{H}}^{ + } } \right]}}} \right)} {\left\{ {\left( {\left[ {{\text{H}}^{ + } } \right] + K_{4} } \right) + \left( {K_{5} \left[ {{\text{H}}^{ + } } \right] + K_{6} K_{4} } \right)\left[ {{\text{IO}}_{4}^{ - } } \right]} \right\}}}} \right. \kern-0pt} {\left\{ {\left( {\left[ {{\text{H}}^{ + } } \right] + K_{4} } \right) + \left( {K_{5} \left[ {{\text{H}}^{ + } } \right] + K_{6} K_{4} } \right)\left[ {{\text{IO}}_{4}^{ - } } \right]} \right\}}} \) where k ₆ (3.65 × 10^?3 s^?1) represents the electron transfer reaction rate constant and K ₄ (4.60 × 10^?4 mol dm^?3) represents the dissociation constant for the reaction \( \left[ {{\text{Cr}}^{\text{III}} \left( {\text{DPA}} \right)\left( {\text{Mal}} \right)\left( {{\text{H}}_{2} {\text{O}}} \right)_{2} } \right]^{ - } \rightleftharpoons \left[ {{\text{Cr}}^{\text{III}} \left( {\text{DPA}} \right)\left( {\text{Mal}} \right)\left( {{\text{H}}_{2} {\text{O}}} \right)\left( {\text{OH}} \right)} \right]^{2 - } + {\text{H}}^{ + } \) and K ₅ (1.87 mol^?1 dm³) and K ₆ (22.83 mol^?1 dm³) represent the pre-equilibrium formation constants at 30 °C and I = 0.2 mol dm^?3. Hexadecyltrimethylammonium bromide (CTAB) was found to enhance the reaction rate, whereas sodium dodecyl sulfate (SDS) had no effect. The thermodynamic activation parameters were estimated, and the oxidation is proposed to proceed via an inner-sphere mechanism involving the coordination of IO₄ ^? to Cr(III).     

A Pitzer Model for Lead Oxide Solubilities in the Presence of Borate to High Ionic Strength

In this study, a hydrolysis model for lead, applicable to high ionic strength, is developed based on lead oxide solubilities as a function of ionic strength. Solubility measurements on lead oxide, α-PbO (tetragonal, red), mineral name litharge, as a function of ionic strength were conducted in NaClO₄ solutions up to I?=?0.45 mol·kg^?1, in NaCl solutions up to I?=?5.0 mol·kg^?1, and in Na₂SO₄ solutions up to I?=?5.4 mol·kg^?1, at room temperature (22.5?±?0.5 °C). The lead hydroxyl species considered in this work include the following,

$$ {\text{PbO}}\left( {\text{cr}} \right) \, + {\text{ 2H}}^{ + } \rightleftharpoons {\text{Pb}}^{ 2+ } + {\text{ H}}_{ 2} {\text{O}}\left( {\text{l}} \right) $$

(1)

$$ {\text{Pb}}^{ 2+ } + {\text{ H}}_{ 2} {\text{O}}\left( {\text{l}} \right) \rightleftharpoons {\text{PbOH}}^{ + } + {\text{ H}}^{ + } $$

(2)

$$ {\text{Pb}}^{ 2+ } + {\text{ 2H}}_{ 2} {\text{O}}\left( {\text{l}} \right) \rightleftharpoons {\text{Pb}}\left( {\text{OH}} \right)_{ 2} \left( {\text{aq}} \right) \, + {\text{ 2H}}^{ + } $$

(3)

$$ {\text{Pb}}^{ 2+ } + {\text{ 3H}}_{ 2} {\text{O}}\left( {\text{l}} \right) \rightleftharpoons {\text{Pb(OH}})_{3}^{ - } + 3{\text{H}}^{ + } $$

(4)

The equilibrium constants for Reactions (1) and (2) were taken from literature. The equilibrium constants in base 10 logarithmic units for Reactions (3) and (4) are determined in this study as ? 17.05?±?0.10 (2σ) and ? 27.99?±?0.15 (2σ), respectively, with a set of Pitzer parameters describing the interactions with Na⁺, Cl^?, and \( {\text{SO}}_{4}^{2 - } .\) In combination with the parameters from literature including those that have already been published by our group, the solution chemistry of lead in a number of media including NaCl, MgCl₂, NaHCO₃, Na₂CO₃, Na₂SO₄, NaClO₄, and their mixtures, can be accurately described in a wide range of ionic strengths.

     

Amphiphilic block copolymers of vinyl ethers by living cationic polymerization. II. Synthesis and surface activity of macromolecular amphiphiles with pendant amino groups

Amphiphilic block polymers of vinyl ethers (VEs). $\rlap{--} [{\rm CH}_{\rm 2} {\rm CH}\left( {{\rm OCH}_{\rm 2} {\rm CH}_{\rm 2} {\rm NH}_{\rm 2} } \right)\rlap{--} ]_m \rlap{--} [{\rm CH}_{\rm 2} {\rm CH}\left( {{\rm OR}} \right)\rlap{--} ]_n \left( {{\rm R: }n{\rm - C}_{{\rm 16}} {\rm H}_{{\rm 33}} ,{\rm }n{\rm - C}_{\rm 4} {\rm H}_{\rm 9} ;m \simeq 40,{\rm n} = 1 - 10} \right)$ were prepared, each of which consists of a hydrophilic segment with pendant primary amino groups and a hydrophobic poly(alkyl VE) segment. Their precursors were obtained by the HI/I₂-initiated sequential living cationic polymerization of an alkyl VE and a VE with a phthalimide pendant (CH₂ = CHOCH₂CH₂Im; Im; phthalimide group), where the segment molecular weights and compositions (m/n ratio) could be controlled by regulating the feed ratio of two monomers and the concentration of hydrogen iodide. Hydrazinolysis of the imide functions gave the target polymers which were readily soluble in water under neutral conditions at room temperature. These amphiphilic block polymers lowered the surface tension of their aqueous solutions (0.1 wt%, 25°C) to a minimum ? 30 dyn/cm when the hydrophobic pendant R was n-C₄H₉ (n = 4–9). The polymers with n-C₄H₉ pendants in the hydrophobic segment exhibited a higher surface activity than those with n-C₁₆ H₃₃ pendants. The surface activity of the polymers also depended on the pH of the polymer solutions; the surface activity increased in more basic solutions where the ionization of the amino group (? NH₂)2? NH₃^⊕) is suppressed.     

Dynamics of Hydration of Alkylsulfonate Anions in Aqueous Solutions

The ¹⁷O-NMR spin-lattice relaxation times (T ₁) of water molecules in aqueous solutions of n-alkylsulfonate (C₁ to C₆) and arylsulfonic anions were determined as a function of concentration at 298 K. Values of the dynamic hydration number, (S^-) = n_h ^- (t_c^- /t_c⁰ - 1)(\mathrm{S}^{-}) = n_{\mathrm{h}}^{ -} (\tau_{\mathrm{c}}^{-} /\tau_{\mathrm{c}}^{0} - 1), were determined from the concentration dependence of T ₁. The ratios (t_c ^-/t_c⁰\tau_{\mathrm{c}}^{ -}/\tau_{\mathrm{c}}^{0}) of the rotational correlation times (t_c ^-\tau_{\mathrm{c}}^{ -} ) of the water molecules around each sulfonate anion in the aqueous solutions to the rotational correlation time of pure water (t_c⁰\tau_{\mathrm{c}}^{0}) were obtained from the n _DHN(S⁻) and the hydration number (n_h ^-n_{\mathrm{h}}^{ -} ) results, which was calculated from the water accessible surface area (ASA) of the solute molecule. The t_c ^-/t_c⁰\tau_{\mathrm{c}}^{ -}/\tau_{\mathrm{c}}^{0} values for alkylsulfonate anions increase with increasing ASA in the homologous-series range of C₁ to C₄, but then become approximately constant. This result shows that the water structures of hydrophobic hydration near large size alkyl groups are less ordered. The rotational motions of water molecules around an aromatic group are faster than those around an n-alkyl group with the same ASA. That is, the number of water–water hydrogen bonds in the hydration water of aromatic groups is smaller in comparison with the hydration water of an n-alkyl group having the same ASA. Hydrophobic hydration is strongly disturbed by a sulfonate group, which acts as a water structure breaker. The disturbance effect decreases in the following order: $\mbox{--} \mathrm{SO}_{3}^{-} > \mbox{--} \mathrm{NH}_{3}^{ +} > \mathrm{OH}> \mathrm{NH}_{2}$\mbox{--} \mathrm{SO}_{3}^{-} > \mbox{--} \mathrm{NH}_{3}^{ +} > \mathrm{OH}> \mathrm{NH}_{2}. The partial molar volumes and viscosity B _V coefficients for alkylsulfonate anions are linearly dependent on their n _DHN(S⁻) values.     

Heat capacity and thermodynamic properties of tellurites Yb2(TeO3)3, Dy2(TeO3)3 and Er2(TeO3)3

The experimental results obtained for the specific molar heat capacity of the tellurites Yb₂(TeO₃)₃, Dy₂(TeO₃)₃ and Er₂(TeO₃)₃ are processed by the least squares method. The temperature dependence of the specific molar heat capacity derived is used to determine the thermodynamic properties: entropy ( \Updelta_T￠^T S_m⁰ ), \left( {\Updelta_{T\prime }^{T} S_{m}^{0} } \right), enthalpy ( \Updelta_T￠^T H_m⁰ ) \left( {\Updelta_{T\prime }^{T} H_{m}^{0} } \right) and Gibbs function ( \Updelta_T￠^T G_m⁰ ) \left( {\Updelta_{T\prime }^{T} G_{m}^{0} } \right) of the tellurites Yb₂(TeO₃)₃, Dy₂(TeO₃)₃ and Er₂(TeO₃)₃.     

Effect of the cathode structure on the electrochemical performance of anode-supported solid oxide fuel cells

The study elementarily investigated the effect of the cathode structure on the electrochemical performance of anode-supported solid oxide fuel cells. Four single cells were fabricated with different cathode structures, and the total cathode thickness was 15, 55, 85, and 85 μm for cell-A, cell-B, cell-C, and cell-D, respectively. The cell-A, cell-B, and cell-D included only one cathode layer, which was fabricated by ( \textLa_0.74 \textBi_0.10 \textSr_0.16 )\textMnO_{3 - d} \left( {{\text{La}}_{0.74} {\text{Bi}}_{0.10} {\text{Sr}}_{0.16} } \right){\text{MnO}}_{{3 - \delta }} (LBSM) electrode material. The cathode of the cell-C was composed of a ( \textLa_0.74 \textBi_0.10 \textSr_0.16 )\textMnO_{3 - d} - ( \textBi_0.7 \textEr_0.3 \textO_1.5 ) \left( {{\text{La}}_{0.74} {\text{Bi}}_{0.10} {\text{Sr}}_{0.16} } \right){\text{MnO}}_{{3 - \delta }} - \left( {{\text{Bi}}_{0.7} {\text{Er}}_{0.3} {\text{O}}_{1.5} } \right) (LBSM–ESB) cathode functional layer and a LBSM cathode layer. Different cathode structures leaded to dissimilar polarization character for the four cells. At 750°C, the total polarization resistance (R _p) of the cell-A was 1.11, 0.41 and 0.53 Ω cm² at the current of 0, 400, and 800 mA, respectively, and that of the cell-B was 1.10, 0.39, and 0.23 Ω cm² at the current of 0, 400, and 800 mA, respectively. For cell-C and cell-D, their polarization character was similar to that of the cell-B and R _p also decreased with the increase of the current. The maximum power density was 0.81, 1.01, 0.79, and 0.43 W cm⁻² at 750°C for cell-D, cell-C, cell-B, and cell-A, respectively. The results demonstrated that cathode structures evidently influenced the electrochemical performance of anode-supported solid oxide fuel cells.     

Synthesis and characterization of silver(I) and heterometallic Cr(III)–Na compounds with the tripodal ligand <Emphasis Type="Italic">N</Emphasis>-(carbamoylmethyl)-iminodiacetatic acid

Using the tripodal ligand N-(carbamoylmethyl)-iminodiacetatic acid (H₂ADA), a two dimensional Ag^I coordination polymer [Ag(HADA)] _n (1) and a mononuclear complex [Cr^III(ADA)₂](H₂O)(H₃O) (2) have been isolated. Using 2 as a precursor, a novel 3D heterometallic compound (3) was obtained. In 1 the singly deprotonated HADA⁻ ligand adopts a novel asymmetrical η₁,η₁,η₂,μ₄-tetradentate coordination mode while in 3 four different coordination modes of ADA²⁻ are observed. The solid-state fluorescence spectrum of 1 shows a maximum at 615 nm whereas no fluorescence emission band was observed for free H₂ADA. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Kinetics and mechanism of oxidation of aquaethylenediaminetetraacetatocobaltate(II) by <Emphasis Type="Italic">N</Emphasis>-bromosuccinimide in aqueous acidic solution

The oxidation of aquaethylenediaminetetraacetatocobaltate(II) [Co(EDTA)(H₂O)]⁻² by N-bromosuccinimide (NBS) in aqueous solution has been studied spectrophotometrically over the pH 6.10–7.02 range at 25 °C. The reaction is first-order with respect to complex and the oxidant, and it obeys the following rate law:

Synthesis of polyamides by the polyaddition of bissuccinimides with diamines

Polyamides which contain succinamide units, ? NHCO? (CH₂)₂? CONH? were prepared by the ring-opening polyaddition of bissuccinimides with diamines at 200°C. in bulk. Nylon 24 and nylon 64 were prepared by the reaction of N,N′-ethylenedisuccinimide with ethylenediamine and of N,N′-hexamethylenedisuccinimide with hexamethylenediamine, respectively. It was suggested that the transamidation reaction by aminolysis influenced the detailed structures of the polymers prepared from N,N′-ethylenedisuccinimide and hexamethylenediamine and from N,N′-hexamethylenedisuccinimide and ethylenediamine. The detailed structures of the polymers are discussed on the basis of their melting points and x-ray diagrams. It is concluded that the polymers contain a crystalline portion of \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--}[{\rm NH \hbox{--} (CH}_2 {\rm)}_{\rm 2} {\rm \hbox{--} NHCO \hbox{--}}({\rm CH}_2)_2 {\rm \hbox{--} CONH \hbox{--}}({\rm CH}_2)_6 {\rm \hbox{--} NHCO \hbox{--}}({\rm CH}_2)_2 {\rm \hbox{--} CO\rlap{---}]} $\end{document} sequences.     

Evaporation Analogies Between Light Hydrocarbons Effect of Molecular Mass of Purge gas

The evaporation of benzene, cyclohexane, n-heptane, toluene, 2-xylene, 3-xylene and 4-xylene was studied in H₂, He, N₂ or CO₂ as purge gases for control of the introduced methods of evaluation and the sensitivity limits of TG measurements. I_i as a function of (1−α) and the following equation proved very suitable for a quantitative comparison of 28 independent and different TG measurements and for a very sensitive characterization of the thermal processes, even within an energy level difference of 3 kJ mol⁻¹, in spite of the known great inconsistency in the formal kinetic parameters:

Kinetics of the gas-phase reaction of acetone with iodine: Heat of formation and stabilization energy of the acetonyl radical

The kinetics of the gas-phase reaction CH₃COCH₃ + I₂ ? CH₃COCH₂I + HI have been measured spectrophotometrically in a static system over the temperature range 340–430°. The pressure of CH₃COCH₃ was varied from 15 to 330 torr and of I₂ from 4 to 48 torr, and the initial rate of the reaction was found to be consistent with \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_3 {\rm COCH}_3 + {\rm I}^{\rm .} \stackrel{1}{\rightarrow}{\rm CH}_{\rm 3} {\rm COCH} + {\rm HI} $\end{document} as the rate-determining step. An Arrhenius plot of the variation of k₁ with temperature showed considerable scatter of the points, depending on the conditioning of the reaction vessel. After allowance for surface catalysis, the best line drawn by inspection yielded the Arrhenius equation, log [k₁/(M^?1 sec^?1)] = (11.2 ± 0.8) – (27.7 θ 2.3)/θ, where θ = 2.303 R T in kcal/mole. This activation energy yields an acetone C? H bond strength of 98 kcal/mole and δH (CH₃CO?H₂) radical = ?5.7 ± 2.6 kcal/mole. As the acetone bond strength is the same as the primary C? H bond strength in isopropyl alcohol, there is no resonance stabilization of the acetonyl radical due to delocalization of the radical site. By contrast, the isoelectronic allyl resonance energy is 10 kcal/mole, and reasons for the difference are discussed in terms of the π-bond energies of acetone and propene.     

P,N-Bidentate Phosphorus Derivatives of (S)-Prolinol

Phosphorylation of (S)-prolinol with P(NEt₂)₃was used to synthesize aminophosphite (2R,5S)- , which was reacted with the corresponding amino alcohols to afford (2S,5R)- (Va) and (2S,5R)- (Vb). Reaction of Vawith [Rh(CO)₂Cl]₂(P/Rh = 1) yields the mononuclear chelate [Rh(CO)(P^N)Cl] (VIIa), while the analogous reaction with Vbresults in a mixture of products with cis- and trans-orientation of the coordinated phosphorus and nitrogen atoms. Spectral characteristics of the products of coordination of ligands Vaand Vbwere compared with those for the binuclear reference complex [Rh(CO)(L)Cl]₂(VIII), where L is P-monodentate ligand (2S,5R)- (VI). The ligands and complexes were studied by IR, NMR, ³¹P and ¹³C spectroscopy, mass spectrometry, and elemental analysis methods. X-ray diffraction analysis of crystals VIIIwas performed.     

Determination of thermodynamic properties of YRhO3(s) by solid-state electrochemical cell and differential scanning calorimeter

The standard molar Gibbs free energy of formation of YRhO₃(s) has been determined using a solid-state electrochemical cell wherein calcia-stabilized zirconia was used as an electrolyte. The cell can be represented by: ( - )\textPt - Rh/{ \textY₂\textO_\text3( \texts ) + \textYRh\textO₃( \texts ) + \textRh( \texts ) }//\textCSZ//\textO₂( p( \textO₂ ) = 21.21  \textkPa )/\textPt - Rh( + ) \left( - \right){\text{Pt - Rh/}}\left\{ {{{\text{Y}}_2}{{\text{O}}_{\text{3}}}\left( {\text{s}} \right) + {\text{YRh}}{{\text{O}}_3}\left( {\text{s}} \right) + {\text{Rh}}\left( {\text{s}} \right)} \right\}//{\text{CSZ//}}{{\text{O}}_2}\left( {p\left( {{{\text{O}}_2}} \right) = 21.21\;{\text{kPa}}} \right)/{\text{Pt - Rh}}\left( + \right) . The electromotive force was measured in the temperature range from 920.0 to 1,197.3 K. The standard molar Gibbs energy of the formation of YRhO₃(s) from elements in their standard state using this electrochemical cell has been calculated and can be represented by: D_\textfG^\texto{ \textYRh\textO₃( \texts ) }/\textkJ  \textmo\textl ^{- 1}( ±1.61 ) = - 1,147.4 + 0.2815  T  ( \textK ) {\Delta_{\text{f}}}{G^{\text{o}}}\left\{ {{\text{YRh}}{{\text{O}}_3}\left( {\text{s}} \right)} \right\}/{\text{kJ}}\;{\text{mo}}{{\text{l}}^{ - 1}}\left( {\pm 1.61} \right) = - 1,147.4 + 0.2815\;T\;\left( {\text{K}} \right) . Standard molar heat capacity C^o_p,m C^{o}_{{p,m}} (T) of YRhO₃(s) was measured using a heat flux-type differential scanning calorimeter in two different temperature ranges from 127 to 299 K and 305 to 646 K. The heat capacity in the higher temperature range was fitted into a polynomial expression and can be represented by: $ {*{20}{c}} {\mathop C\nolimits_{p,m}^{\text{o}} \left( {{\text{YRh}}{{\text{O}}_3},{\text{s,}}T} \right)\left( {{\text{J}}\;{{\text{K}}^{ - 1}}{\text{mo}}{{\text{l}}^{ - 1}}} \right)} & { = 109.838 + 23.318 \times {{10}^{ - 3}}T\left( {\text{K}} \right)} & { - 12.5964 \times {{10}^5}/{T^2}\left( {\text{K}} \right).} \\ {} & {\left( {305 \leqslant T\left( {\text{K}} \right) \leqslant 646} \right)} & {} \\ $ \begin{array}{*{20}{c}} {\mathop C\nolimits_{p,m}^{\text{o}} \left( {{\text{YRh}}{{\text{O}}_3},{\text{s,}}T} \right)\left( {{\text{J}}\;{{\text{K}}^{ - 1}}{\text{mo}}{{\text{l}}^{ - 1}}} \right)} & { = 109.838 + 23.318 \times {{10}^{ - 3}}T\left( {\text{K}} \right)} & { - 12.5964 \times {{10}^5}/{T^2}\left( {\text{K}} \right).} \\ {} & {\left( {305 \leqslant T\left( {\text{K}} \right) \leqslant 646} \right)} & {} \\ \end{array} The heat capacity of YRhO₃(s) was used along with the data obtained from the electrochemical cell to calculate the standard enthalpy and entropy of formation of the compound at 298.15 K.